ABB RELION REX640 Technical Manual page 1424

Section 9
Control functions
1418
No adjustment takes place between 1/3 and 2/3 of smax. The adjusting pulse is
discontinued as soon as the slip passes through zero. The command length does not
fall below a settable Freq pulse Min Dur. After an adjusting command, the system
waits for the set Freq pulse off Intv so that the actual values can stabilize to the new set
point.
GUID-2715B7CC-7180-41F5-B99B-2C36A5DCD9A2 V1 EN
Figure 762: Working range of the frequency matcher
If Auto Syn mode is set to either "Semi-automatic synchronizing mode" or "Automatic
synchronizing mode", the frequency raise or lower command pulses are generated
from the function based on the frequency difference across the CB and governor
response characteristics.
If the frequency difference (DF) is negative, the reference side frequency is greater
than the running side frequency. So the frequency matching generates frequency raise
command pulse RAISE_F.
1MRS759142 C
REX640
Technical Manual